Supernova Remnants in X-Rays and Infrared: 0453.1-66.55 and DEM L204

Recent observations of supernova remnants (SNR) with the Spitzer Space Telescoperevealed that thermal dust emission dominates their infrared (IR) spectra. IRemission was detected mostly in Xray bright SNRs, but it is also present inseveral older and fainter SNRs. We propose an Xray study of two such IRremnants, 0453.166.55 and DEM L204. The origin of IR emission and the nature ofthese SNRs are not understood. Xray imaging with the XMMNewton EPIC camerawill reveal location of the hot gas relative to optical and IR emission,allowing us to understand the origin of the IR emission. Xray spectroscopy willprovide as with temperatures and abundances of the hot gas. We will learn aboutdust content, energetics, and the evolutionary state of these unusual infrared SNRs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]